Objective To observe whether theograde axial flow of retinal ganglion cells (RGC) in diabetic rats at the early stage was damaged. Methods Diabetic model was induced by streptozotocin in 6 adult male Sprague-Dawley (SD)rats. Fluorogold (FG) was injected to the superior colliculi 4 weeks later.Streched preparation of retina was made 12 and 72 hours after the injection, and was stained after photographed by fluorescent microscope. The proportion of RGC with different sizes labeled by FG was calculated. Other 6 normal adult male SD rats were in the control group. Results Twelve hours after injection with FG, there was no difference of the total number of RGC in experimental and control group, but the ratio of small RGC was lower in experimental group than that in the control group; 72 hours after injection with FG, The number of RGC, especially the small RGC, decreased obviously in experimental group compared with the control group. Conclusion The speed of the retrograde axial flow of RGC in diabetic rats at the early stage is affected, and the small RGC are damageable. (Chin J Ocul Fundus Dis, 2006, 22: 4-6)
Objective To demonstrate if apoptosis is one of the mechanisms of siderotic retinopathy. Methods Autoclaved iron particles were implanted in the vitreous cavities of 32 eyes of SD rats.Glass chips were implanted in 10 control eyes.The experimental eyes were enucleated at various time intervals from days 1 to 15.Retinal degeneration was examined using the TdT-mediated,dUTP-biotin nickend labeling(TUNEL)method.Electrophoresis on agarose gel was used to detect internucleosomal DNA fragmentation.Results TUNEL-positive nuclei were observed only in the outer nuclear layer beginning on day 2.The nuclei spread throughout the outer nuclear layer by the end of day 3.No TUNEL-positive nuclei were observed in other layers throughout the experimental perios.Analysis of DNA,extracted from the retinas by electrophoresis on agarose gel,revealed a typical ladder pattern of internucleosoma DNA cleavage in the experimental eyes.ConclusionApoptosis of photoreceptors occurs at the early phase of iron-induced retinopathy in the rats.
ObjectiveTo observe the effects of Rhodiola on the rat retinal tissue morphology and the hypoxia-inducible factor (HIF)-1α at simulated hypoxia at different altitudes. Methods Forty-eight adult female Sprague Dawley rats were randomly divided into the Rhodiola Intervention group (intervention group) and the control group, each group had 24 rats. The intervention group rats were treated with intraperitoneal injection of 10 ml/kg of large plants Rhodiola solution, and the control group rats were injected with same volume of saline. One hour after the injection, six rats were randomly selected from both of the two groups and reared in the plateau environment simulation laboratory modules with the oxygen partial pressure of 17.4, 14.6, 11.3 and 7.4 kPa, which simulated the altitudes of 1500, 3000, 5000 and 8000 meters indoor respectively. Six hours later the rat eyeballs were harvested for paraffin sections and analyzed by hematoxylin and eosin staining, and immunohistochemical staining to observe the expression of HIF-1α and p53. ResultsIn the control group, the rat retinal layers were edema and loose, the retinal thickness increased, the retinal structure was disorganized, the ganglion cells were swollen and degenerated, and some can observe the karyopyknosis, karyolysis and the reduced cells number. As the altitude increased, the pathological changes of retinal became more obvious. In the intervention group, the characteristics of rat retinal morphology were same with the control group, while the degree of morphology changes was lighter than the control group. HIF-1α and p53 expressed mainly in the ganglion cell layer and inner nuclear layer of rat retina in the control group. As altitude increased, the expression of HIF-1α and p53 were increased too, which was positive correlated (r=0.9846, P < 0.05). Compared with the control group, the rat retinal expression of HIF-1α increased, while expression of p53 decreased in the intervention group, and the differences were statistically significant (P < 0.05). ConclusionRhodiola can reduce the retinal tissue pathology damage caused by high altitude hypoxia, and its mechanism may be related to the increasing expression of HIF-1α and reducing expression of p53.
Objective To observe the morphological changes of dendrite and soma in retinal ganglion cells (RGCs) which subsisted in early diabetic rats. Methods The RGCs of 3-months-course diabetic rats and coeval normal rats were marked by gene gun techniques. To collect RGCs photographs by Leica microscope with Z axis and CCD camera；to observe the changes of diameter, variance of structural features in dendritic field and somata after classification which according to the size and morphology. Thy-1 antibody marks on the retinal RGCs, taking a photograph under fluorescent microscope, counting the changes of retinal RGCs density in early diabetic rat. Results In three-month diabetic rats,the density of retinal RGCs was decreased obviously. Morphological changes of RGCs in the dendritic fields were observed with gene gun technique. There was no severe variation in all kinds of the bole of cell dendrite, in which some only showed crispation partially and sparseness also twisting in the dendritic ramus. The mean diameter of dendritic field and soma in class A of diabetic rats was (401plusmn;86) mu;m, the mean diameter of dendritic field in control group was (315plusmn;72) mu;m,compared with each other, there is statistically significant differences (t=21.249，Plt;0.001); the mean diameter of soma in class A of diabetic rats was (24plusmn;6) mu;m, the mean diameter of soma in control group was (22plusmn;5) mu;m, compared with each other, there is no statistically significant differences (t=0.927，Pgt;0.05); the mean diameter of dendritic field and soma in class B of diabetic rats were (170plusmn;36)、(14plusmn;2) mu;m respectively, in control group were (165plusmn;36)、(16plusmn;2) mu;m, the mean diameter of dendritic field and soma in class C of diabetic group were(265plusmn;78)、(17plusmn;5) mu;m respectively, in control group were (251plusmn;57)、(17plusmn;4) mu;m , compared with each other, there are on statistically significant differences(t=1.357，0.798，0.835，1.104，Pgt;0.05). Conclusions In short-term diabetes, the survived RGCs show good plasticity in adult diabetic rats, especially in class A. The changes of dendrites were more sensitive than the soma, which could be the leading index of the morphologic changes of RGCs in the early stage. The good plasticity showed by the RGCs and the time window from changing in dendrite to cell death provide us many evidences not only for the research but also for the nerve protection in clinic. (Chin J Ocul Fundus Dis,2008,24:249-254)
ObjectiveTo observe the expression of Toll-like receptor 4 (TLR4) and inflammatory cytokines, leucocytic density and permeability in retina of diabetic rat. MethodsA total of 106 Brown Norway rats were randomly divided into experimental group and control group with 53 rats in each group. Diabetic model was established in experimental group by intraperitoneal injection of streptozotocin, and control rats received intraperitoneal injection of an equal volume of citric acid-sodium citrate buffer. Four weeks later, the retinas were collected for further analysis. TLR4 RNA and protein expression were measured by quantitative polymerase chain reaction and Western blot. Inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), monocyte chemo-attractant protein-1 (MCP-1), were measured by enzyme-linked immunosorbent assay in rat retina homogenate. Leukocyte density in the retina was measured by acridine orange fundus angiography. The retinal permeability was evaluated by Evans blue (EB) staining. ResultsTLR4 expression was significantly increased in diabetic rats of experimental group compared with non-diabetic rats of control group (F=1.606, 0.789; P < 0.05). Inflammatory cytokines (TNF-α, IL-1β and MCP-1) were significantly increased in retina of diabetic rats of experimental group versus non-diabetic rat of control group (F=24.622, 5.758, 4.829; P < 0.05). The retinal leukocyte density was (6.2±0.5)×10-5, (2.2±0.3)×10-5 cells/pixel2 in experimental and control group respectively, the difference was statistically significant (F=2.025, P < 0.05). The amount of retinal EB leakage was (23.41±4.47), (13.22±3.59) ng/mg in experimental and control group respectively, the difference was statistically significant (F=21.08, P < 0.05). ConclusionTLR4 and inflammatory cytokines expression, leucocytic density and permeability increased significantly in retina of diabetic rat.
ObjectiveTo observe the protective effect of Zhicao Tea Mixture on Müller cells and the expression of inflammatory factors in mice with diabetic retinopathy.MethodsSeventy-five C57BL/6J mice were randomly divided into the normal control group, diabetes mellitus (DM) group, low concentrations group, medium concentrations group and high concentrations group, with 16 mice in each group. The diabetes model of mice in all groups except the normal control group were established by intraperitoneal injection of STZ (60 mg/kg). Four weeks after the successful modeling, the Zhicao Tea Mixture with low (30 ml/kg), medium (60 ml/kg) and high concentrations (120 ml/kg) were respectively administered by gavage. Weight and blood glucose of mice in each group were measured every two weeks. After 8 weeks, Western blot method was used to detect the mice retina Müller cells activation marker gelatinous fibrous acidic protein (GFAP). Immunofluorescence was performed to detect the expression GFAP and glutamine synthetase (GS). Real-time quantitative PCR (RT-qPCR) and ELISA were used to determine the mRNA and protein expression levels of mouse retinal VEGF, TNF-α, IL-1β and IL-6 respectively.ResultsThe weight of mice in the DM group was lower than that of the normal control group, and the blood glucose was increased. Zhicao Tea Mixture had no effect on the weight of DM mice, but had a significant hypoglycemic effect. The GFAP expression (t=38.318, P＜0.001) in the retina of mice in the DM group was increased and GS expression (t=29.737, P＜0.001) was decreased compared with the control group. The GFAP expression (t=13.677, 19.387, 16.305; P＜0.05) in the retina of mice in the low, medium and high concentrations group were decreased and GS expression (t=5.170, 19.399, 6.705; P＜0.05) were increased compared with the DM group. The expressions of retinal inflammatory factors VEGF, TNF-α, IL-1β and IL-6 in DM group all increased, while the expressions of the above-mentioned inflammatory factors in the retina of mice decreased in the low, medium and high concentrations group.ConclusionZhicao Tea Mixture can decrease the blood glucose of DM mice and reduces the diabetic retinal inflammatory response.